It is known in the technology that air flow is generated incident to the rotation of data storage discs in a disc drive. The characteristics of the air flow have been analyzed and discussed in the prior art, as for example, U.S. Pat. No. 4,647,997 to Westwood, and in the IBM Journal of Research and Development, November 1974, pages 480-488. It is known that two commonly mounted spaced apart rotating discs generate a significantly greater air flow than generated by a single rotating disc, and that the amount of air flow is also known to be a function of disc diameter and angular velocity. The air flow force is greatest adjacent the periphery of the rotating disc and especially at the region defined between two rotating discs, and fall off rapidly as a non-linear function as one moves away from the disc periphery.
In rotating, non-removable data disc storage devices, a data read/write transducer flies upon an air cushion or bearing in extremely close proximity to the data surface. In many disc drives, including those which are of extremely small size, that transducer lands upon and takes off from a particular predefined landing region. It is possible, when shocks are applied to the disc drive, that the transducer can move or bounce across the surface of the disc, causing erosion or scarring of the magnetic film coating on the disc surface leading to hard and soft data failures. In addition, the hard transducer head may dent the surface in response to sharp jarring forces attributable to sharp or rough handling of the drive.
While aerodynamically actuated latches have been described in the above referenced Westwood patent as well as in U.S. Pat. No. 4,538,193, such latches have not been effective because of a lack of the sensitivity and responsiveness to the limited air flow in extremely small size disc drives to be effective. It has been found that the air flow values in such small disc drives must be carefully accounted for and are, in many cases, too small in magnitude to effectively, reliably and responsibly release the actuator when the discs begin rotation. Further, the spring force that restrains the transducer actuator assembly in the landing zone must be carefully selected so that the force can be overcome when the discs begin to move.
Thus, a need has arisen for a reliable, responsive, air flow responsive latch mechanism responsive to the air flow generated in a small form factor disc drive to reliably latch and release the actuator mechanism, while restraining the actuator against relatively strong shocks.